Last night I logged data using EFI for the first time on my LB7. I'm trying to diagnose an intermittent low power issue on it. My initial thought was that the suction side of my cp3 might be getting weak, so in an attempt to diagnose it, I logged RPM, throttle position, desired fuel rail pressure, actual fuel rail pressure, fuel rail pressure (I'm not sure what the significance of this parameter is compared to the other FRP's), and boost. I was surprised to see that my desired and actual fuel rail pressure fell right on top of each other, so I believe that would rule out a fuel starvation issue.

One thing I did note though, was that I see a big difference in boost between a run when the truck pulled stronger versus a "weak" run. On the weak runs, I was only seeing a few pounds of boost over atmospheric.

I'll post the .efi log files tonight from home. In the meantime, does anyone have any thoughts on what would be a likely cause for a low boost situation? Leaking boost line? Bad wastegate actuator?

Thanks in advance